Heat sink

ABSTRACT

A heat sink that can reduce a load imposed on a heat pipe and enhance a heat transfer efficiency from a heating body to a heat radiation fin is provided. 
     The heat sink has a base plate  21  having a heat receiving portion to which a semiconductor device  11  is thermally connected, a heat pipe disposed on the base plate  21  while partially brought into contact with the heat receiving portion, and a heat radiation fin arranged to be stacked on the base plate  21  and the heat pipe  22 . The base plate  21  is formed of a metal plate and has an opening portion  35  at the site corresponding to the heat receiving portion, and the heat receiving plate  36  which is formed of a metal plate having higher thermal conductivity than the base plate  21  is arranged to form substantially the same plane with the base plate  21.

TECHNICAL FIELD

The present invention relates to a heat sink having a heat pipe disposed in a base plate.

BACKGROUND ART

There is generally known a heat sink that has a base plate having a heat receiving portion to which a heating body is thermally connected, a heat pipe disposed in the base plate so as to come into partial contact with the heat receiving portion, and a heat radiation fin which is thermally connected to the heat pipe (see Patent Document 1, for example).

PRIOR ART Patent Document

Patent Document 1: Japanese Patent No. 4,999,060

SUMMARY OF THE INVENTION Problem to be Solved by the Invention

In order to efficiently transfer heat from the heating body to the heat radiation fin through the heat pipe in this type of heat sink, the base plate which is brought into contact with the heat pipe is desired to be formed of a material having excellent thermal conductivity (for example, copper, copper alloy or the like). However, when the whole body of the base plate is formed of copper or copper alloy, the amount of copper to be used increases, and causes a problem that the weight and the manufacturing cost increase.

Furthermore, heat sinks are strongly required to be designed in compact size. However, when the heat radiation fin is mounted while stacked on the base plate, the heat pipe is sandwiched between the base plate and the heat radiation fin, and thus it is desired to reduce a load applied to the heat pipe.

The present invention has been implemented to solve the above problem, and has an object to a heat sink that can reduce a load applied to a heat pipe, and also enhance the heat transfer efficiency from a heating body to a heat radiation fin.

Means of Solving the Problem

The specification of this application contains the whole content of Japanese Patent Application No. 2012-267171 filed on Dec. 6, 2012.

In order to attain the above object, according to the present invention, a heat sink comprises a base plate having a heat receiving portion to which a heating body is thermally connected, a heat pipe disposed on the base plate while partially brought into contact with the heat receiving portion, and a heat radiation fin disposed to be stacked on the base plate and the heat pipe, wherein the base plate is formed of a metal plate and has an opening portion at a site corresponding to the heat receiving portion, and the heat receiving portion formed of a metal plate having higher thermal conductivity than the base plate is placed at the opening portion so that one surface of the heat receiving plate and a surface of the base plate on which the heat pipe is mounted form substantially the same plane.

In the above construction, the base plate may be formed by folding a metal plate to have a groove portion on which the heat pipe is mounted, and a mount portion which is formed at both the sides of the groove portion and on which the heat radiation fin is mounted, the opening portion is equipped in the groove portion, and the surface of the groove portion and the back surface of the mount portion are formed at the same height. Furthermore, the heat receiving plate may be fixed to the back surface of the mount portion.

Furthermore, the heat radiation fin may have a plurality of fin plates equipped side by side, and the fin plates may be arranged along an extension direction of the heat pipe. the heat radiation fin has a plurality of reception grooves for receiving the heat pipe on a surface thereof which confronts the base plate, and a leg portion that comes into contact with the surface of the base plate may be equipped between the reception grooves.

Effect of the Invention

According to the present invention, the base plate is formed of the metal plate and has the opening portion at the site corresponding to the heat receiving portion. The heat receiving portion which is formed of a metal plate having higher thermal conductivity than the base plate is equipped at the opening portion. Therefore, heat from a heating body can be efficiently transferred to the heat radiation fin through the heat receiving portion and the heat pipe. Furthermore, the heat receiving plate is arranged within substantially the same plane (substantially in-plane) as the surface of the base plate on which the heat pipe is mounted, and thus occurrence of a step on the base plate can be prevented. Even when the heat radiation fin is arranged to be stacked on the base plate and the heat pipe, an excessively load can be prevented from being imposed on the heat pipe.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view showing a heat sink according to a first embodiment.

FIG. 2 is a perspective view showing the external appearance of the heat sink.

FIG. 3 is a side view showing the heat sink.

FIG. 4 is a side cross-sectional view of the heat sink.

FIG. 5 is a plan view of a base plate before press forming.

FIG. 6 is a side view showing a heat sink according to another embodiment.

FIG. 7 is a side cross-sectional view of the heat sink.

MODES FOR CARRYING OUT THE INVENTION

A first embodiment according to the present invention will be described hereunder with reference to the drawings.

First Embodiment

FIG. 1 is an exploded perspective view showing a heat sink 10 according to a first embodiment, and FIG. 2 is a perspective view showing the external appearance of the heat sink 10.

The heat sink 10 is used for an electronic device such as a personal computer or the like, for example, and it is thermally connected to a semiconductor device (heating body) 11 such as CPU or the like mounted on a circuit board (not shown) to cool the semiconductor device 11.

As shown in FIG. 1, the heat sink 10 has a flat-plate type base plate 21, plural (three in this embodiment) heat pipes 22 are arranged side by side on the base plate 21, and plural (two in this embodiment) heat radiation fins 23 are arranged side by side while stacked on the base plate 21 and the heat pipes 22. That is, in this construction, the heat pipes 22 are sandwiched and held between the base plate 21 and the heat radiation fins 23 as shown in FIG. 2.

The base plate 21 is formed by folding a metal plate of aluminum or the like through press forming. As shown in FIG. 1, the base plate 21 has a wide groove portion 31 extending in the longitudinal direction (in the direction of Y in FIG. 1) substantially at the center in the short-length direction (in the direction of X in FIG. 6), and a pair of bank portions (mount portions) which are disposed at both the sides of the groove portion 31 and formed to be higher than the groove portion 31. These bank portions 32 are formed at substantially the same height position, and each of the edge portions 33 thereof is folded downwards. The heat pipes 22 are mounted on the groove portion 31, and the heat radiation fins 23 are mounted on the bank portions 32.

Hole portions 34 are formed at two positions of each bank portion 32 (totally, four positions). These hole portions 34 are holes through which fixing screws for fixing the heat sink 10 to a circuit board penetrate.

The groove portion 31 is placed substantially at the center in the width direction of the base plate 21, but the present invention is not limited to this style. The groove portion 31 may be placed at any position in the width direction.

This type of base plate may be formed not only by folding a metal plate, but also by a die-casting method, an extrusion molding method or a cutting method. However, the die-casting method and the extrusion molding method need a cost for dies or molds, and thus these methods are not suitable for small production. Even the cutting method has a problem that a processing cost and a material cost are increased. Furthermore, since a die-cast product is generally inferior to a metal plate in thermal conductivity, the cooling performance is fluctuated in accordance with the difference in thermal conductivity of the base plate when the other conditions are identical.

On the other hand, according to this construction, the base plate 21 is formed by folding a metal plate through press forming. This construction can enhance the thermal conductivity of the base plate 21 itself, and also reduce the manufacturing cost as compared with the foregoing methods. Furthermore, the groove portion 31 and the edge portions 33 which are folded in the base plate 2 function as reinforcing ribs, so that the base plate 21 can be configured to be light and thin while securing stiffness.

In this construction, the base plate 21 has an opening portion 35 substantially at the center in the longitudinal direction of the groove portion 31 (the position corresponding to a heat receiving portion to be thermally connected to the semiconductor device 11), and a heat receiving plate 36 which is formed of metal having higher thermal conductivity (for example, copper) than the base plate 21 is mounted at the opening portion 35. The semiconductor device 11 is connected to the back surface (lower surface in FIG. 1) 36A of the heat receiving plate 36, and the heat receiving plate 36 is fixed while the heat pipes 22 are partially brought into contact with the surface (upper surface in FIG. 1) 36B of the heat receiving plate 36.

In the construction, heat generated from the semiconductor device 11 is transferred to the heat pipes 22 through the heat receiving plate 36. Since the heat receiving plate 36 is formed of the metal having higher thermal conductivity than the base plate 21, the heat of the semiconductor device 11 can be rapidly transferred to the heat radiation fins 23 through the heat receiving plate 36 and the heat pipes 22, and the cooling performance of the heat sink 10 can be enhanced. Furthermore, the weight can be reduced, and the costs for materials and manufacturing can be more greatly reduced as compared with a case where the whole body of the base plate 21 is formed of copper.

The heat pipes 22 are members for diffusing the heat received by the heat receiving plate 36 to the heat radiation fins 23. For example, the heat pipe 22 is formed by encapsulating operating fluid such as water or the like under pressure-reduced state in a hermetically sealed container which is formed of metal having excellent thermal conductivity such as copper or the like or formed of alloy of the metal. The container is configured in a flat shape to reduce the height (thickness) thereof and secure a large contact area with the base plate 21 and the heat radiation fins 23. The heat pipes 22 are fixed to the groove portion 31 of the base plate 21 and the heat receiving plate 36 by soldering, brazing or the like.

The heat radiation fin 23 serves to discharge the heat transferred through the heat pipes 22 into air, and is configured to have the substantially half length of the heat pipes 22. Two heat radiation fins 23 are arranged side by side in the extension direction of the heat pipes 22. The heat radiation fins 23 are formed in a region containing an area just above the heat receiving plate 36, and exist over a broad area on the base plate 21. The number of the heat radiation fins 23 to be arranged may be arbitrarily changed in accordance with the length of the heat pipes 22, and it is needless to say that they may be configured as a single heat radiation.

Each heat radiation fin 23 has plural fin plates 43 each of which is formed to have a substantially U-shaped cross-section by folding an upper edge 41 and a lower edge 42 of a metal plate 40 of aluminum or the like substantially in parallel to each other, for example.

These fin plates 43 are arranged side by side in the extension direction of the heat pipes 22, and the respective fin plates 43 are fixed integrally with one another by soldering, for example. Air is allowed to flow through the gap between the adjacent fin plates 43. Therefore, the heat transferred to the heat pipes 22 can be diffused to the whole bodies of the heat radiation fins 23, and this heat can be heat-exchanged with air flowing through the gap between the fin plates 43, whereby the heat can be radiated.

Reception grooves 24 in which the heat pipes 22 are received are formed on the lower surface (confronting surface) 23A of the heat radiation fin 23 which confronts the base plate 21 and the heat pipes 22. The reception groove 24 is formed in conformity with the outer shape of the heat pipe 22, and enhances the thermal transfer area between the heat pipe 22 and the heat radiation fin 23.

A leg portion 25 is equipped between the respective reception grooves 24, and these leg portions 25 come into contact with the surface of the groove portion 31 of the base plate 21 (the surface on which the heat pipes 22 are mounted) 31A when the heat radiation fins 23 are mounted on the bank portions 32 of the base plate 21, whereby thermal conduction can be directly performed from the base plate 21 to the heat radiation fins 23 through the leg portions 25, and the load of the heat radiation fins 23 is supported by the leg portions 25, thereby reducing the load applied to the heat pipes 22.

In this embodiment, the heat radiation fins 23 are fixed to the base plate 21 and each heat pipe 22 by soldering or the like, whereby the heat sink 10 is integrally configured. Furthermore, the heat radiation fins 23 are equipped with cut-out portions at the positions corresponding to the hole portions 34 formed in the base plate 21.

In the heat sink 10 described above, in order to enhance the thermal conductivity of the base plate 12 with an inexpensive construction, the base plate 21 is formed by folding a metal plate, the opening portion 35 is formed at the position corresponding to the heat receiving portion which is thermally connected to the semiconductor device 11, and the heat receiving plate 36 formed of metal having higher thermal conductivity than the base plate 21 is disposed at the opening portion 35.

The heat sink 10 is configured by stacking the heat radiation fins 23 on the base plate 21, and thus the heat pipes 22 are sandwiched between the base plate 21 and the heat radiation fins 23. Therefore, it is desired to reduce the load of the heat radiation fins 23 imposed on the heat pipes 22.

Therefore, in this construction, the heat receiving plate 36 is disposed so that no step or a remarkably slight step exists between the surface (upper surface; one surface in the FIG. 36B of the heat receiving plate 36 and the surface (upper surface in the FIG. 31A of the groove portion 31 of the base plate 21, that is, the surface 36B of the heat receiving plate 36 and the surface 31A of the groove portion 31 of the base plate 21 are arranged to form substantially the same plane (are arranged substantially within the same plane).

Specifically, as shown in FIG. 3, the base plate 21 is formed by folding the metal plate so that the surface 31A of the groove portion 31 and the back surfaces (lower surfaces in FIG. 3) of the bank portions 32 are located at the same height position, and the heat receiving plate 36 is configured to be larger in width than the groove portion 31 and fixed to the back surfaces 32A of the bank portions 32 by soldering or the like.

Accordingly, the surface 36B of the heat receiving plate 36 and the surface 31A of the groove portion 31 can form substantially the same plane (be arranged within substantially the same plane) and the heat receiving plate 36 can be arranged at the opening portion 35 of the base plate 21 by a simple work of applying the heat receiving plate 36 to the opening portion 35 from the side of the back surfaces 32A of the bank portions 32 and fixing the heat receiving plate 36 to the back surfaces 32A as shown in FIG. 4. Therefore, the step between the heat receiving plate 36 and the base plate 21 can be prevented, and even when the heat radiation fins 23 are stacked and arranged on the base plate 21 and the heat pipes 22, an excessively load can be prevented from being imposed on the heat pipes 22.

Next, a method of forming the base plate 21 will be described.

FIG. 5 is a plan view before press forming of the base plate 21.

First, a metal plate is punched out to have an outer shape shown in FIG. 5, and an opening portion 35 and hole portions 34 are formed at predetermined positions.

Subsequently, the punched metal plate is folded to have a desired shape by press forming. Specifically, the punched metal plate is mountain-folded along lines 50 extending thereon while the lines 50 are spaced inwards from the edges of the metal plate by a predetermined distance, and lines 51 extending along the edge portions 35A of the opening portion 35, and also valley-folded along lines 52 extending thereon while the lines 52 are spaced inwards from the lines 51 by a predetermined distance, thereby forming the base plate 21.

In this case, recess portions 35B extending outwards from the edge portions 35A are formed at the four corners of the edge portions 35A of the opening portion 35. Accordingly, when the metal plate is folded along the lines 51, spreading at the four corners of the opening portion 35 can be prevented, and the metal plate can be accurately folded along the edge portions 35A of the opening portion 35.

As described above, the heat sink according to this embodiment comprises the base plate 21 having the heat receiving portion to which the semiconductor device 11 is thermally connected, heat pipes 22 disposed on the base plate 21 while partially coming into contact with the heat receiving portion, and the heat radiation fins 23 disposed to be stacked on the base plate 21 and the heat pipes 22, the base plate 21 is formed of a metal plate and has the opening portion 35 at the site corresponding to the heat receiving portion, and the heat receiving plate 36 formed of a metal plate having higher thermal conductivity than the base plate 21 is equipped at the opening portion 35. Therefore, heat from the semiconductor device 11 can be efficiently transferred to the heat radiation fins 23 through the heat receiving plate 36 and the heat pipes 22. Furthermore, the heat receiving plate 36 forms substantially the same plane with (is arranged within substantially the same plane as) the surface 31A of the base plate 21 on which the heat pipes 22 are mounted. Therefore, occurrence of a step on the base plate 21 is prevented, and even when the heat radiation fins 23 are arranged to be stacked on the base plate 21 and the heat pipes 22, an excessive load can be prevented from being applied to the heat pipes 22.

According to this embodiment, the base plate 21 is formed by folding the metal plate, and has the groove portion 31 on which the heat pipes 22 are mounted, and the bank portions 32 which are mounted at both the sides of the groove portion 31 and on which the heat radiation fins 23 are mounted. The opening portion 35 is formed in the groove portion 31, and the surface 31A of the groove portion 31 and the back surfaces 32A of the bank portions 32 are formed at the same height. Therefore, the heat receiving plate 36 can be disposed at the opening portion 35 of the base plate 21 so that the surface 36B of the heat receiving plate 36 and the surface 31A of the groove portion 31 form substantially the same plane (are arranged within substantially the same plate) by s simple work of applying the heat receiving plate 36 from the side of the back surfaces 32A of the bank portions 32 to the opening portion 35 and fixing the heat receiving plate 36 to the back surfaces 32A.

According to this embodiment, since the heat receiving plate 36 is fixed to the back surfaces 32A of the bank portions 32, the fixing structure can be simplified, and the fixed portion is not exposed to the outside, so that the external appearance of the heat sink 10 can be enhanced.

Furthermore, according to this embodiment, the heat radiation fin 23 has plural fin plates 43 arranged side by side, and these fin plates 43 are arranged along the extension direction of the heat pipes 22. Therefore, heat transferred through the heat pipes 22 can be diffused to each of the fin plates 43, and the heat can be heat-exchanged with air flowing through the gap between the fin plates 43 to be radiated.

Still furthermore, according to this embodiment, the heat radiation fin 23 has the plural reception grooves 24 for accommodating the heat pipes 22 on the lower surface 23A thereof which confronts the base plate 21, and the leg portions 25 which come into contact with the surface 31A of the groove portion 31 of the base plate 21 are equipped between the reception grooves 24A. Therefore, when the heat radiation fins 23 are mounted on the bank portions 32 of the base plate 21, the leg portions 25 come into contact with the surface 31A of the groove portion 31 of the base plate 21, whereby thermal conduction can be directly performed from the base plate 21 through the leg portions 25 to the heat radiation fins 23. Furthermore, the load of the heat radiation fins 23 can be supported by the leg portions 25, and thus the load imposed on the heat pipes 22 can be reduced.

Second Embodiment

Another embodiment of the heat sink will be described. The heat sink 100 of the second embodiment is different from the first embodiment in the shape of the base plate. In the second embodiment, only the structural difference will be described. The same constituent elements are represented by the same reference numerals, and the descriptions thereof are omitted.

FIG. 6 is a side view showing the heat sink 100 according to the second embodiment, and FIG. 7 is a side cross-sectional view showing the heat sink 100.

The base plate 121 of this embodiment is formed by a metal plate which has not been subjected to the folding (bending) work. In this embodiment, the heat receiving plate 36 is formed to have substantially the same size as the opening portion 135 formed in the base plate 121 and the heat receiving plate 36 is fixed to the opening portion 135 so that the surface 36B of the heat receiving plate 36 and the surface (upper surface in FIG. 6) 121A of the base plate 121 form substantially the same plane (are arranged within substantially the same plane).

Specifically, a backing pad is disposed at the surface 121A side of the base plate 121 (the surface on which the heat pipes 22 are mounted), and the base plate 121 and the heat receiving plate 36 are fixed to each other from the back surface 121B side of the base plate 121 by soldering or the like while the surface 36B of the heat receiving plate 36 is brought into contact with the backing plate. In this construction, a higher skill is needed to fix the heat receiving plate as compared with the first embodiment. However, the surface 36B of the heat receiving plate 36 and the surface 121A of the base plate 121 can form substantially the same plane (be arranged within substantially the same plane).

According to this embodiment, the thickness of the base plate 121 can be reduced, and thus the heat sink 100 can be configured to be thin.

The present invention has been specifically described on the basis of the embodiments. However, the present invention is not limited to the above embodiments, and the embodiments may be modified without departing from the subject matter of the present invention.

For example, in the above embodiments, the three heat pipes 22 are mounted on the base plate 21, 121, but the number of heat pipes 22 may be arbitrarily changed. The heat pipe 22 is configured to be flat, but it may be configured in a round shape.

In the above embodiments, the opening portion 35, 135 is equipped substantially at the center of the base plate 21, 131. However, the present invention is not limited to this style, and the locating position thereof may be changed in accordance with the position of the semiconductor device 11 mounted in the circuit board. Furthermore, in the above embodiments, the semiconductor device 11 mounted on the circuit board is set as a heating body. However, the present invention is not limited to this style.

DESCRIPTION OF REFERENCE NUMERALS

-   -   10, 100 heat sink     -   11 semiconductor device (heating body)     -   21, 121 base plate     -   22 heat pipe     -   23 heat radiation fin     -   23A lower surface (confronting surface)     -   24 reception groove     -   25 leg portion     -   31 groove portion     -   31A, 121A surface (surface on which heat pipes are arranged)     -   32 bank portion     -   32A back surface     -   35, 135 opening portion     -   36 heat receiving plate     -   36B surface     -   43 fin plate 

1. A heat sink comprising: a base plate having a heat receiving portion to which a heating body is thermally connected; a heat pipe disposed on the base plate while partially brought into contact with the heat receiving portion; and a heat radiation fin disposed to be stacked on the base plate and the heat pipe, wherein the base plate is formed by folding a metal plate, and has a groove portion on which the heat pipe is mounted, and a mount portion which is located at both the sides of the groove portion and on which the heat radiation fin is mounted, an opening portion is formed at a site corresponding to the heat receiving portion of the groove portion, and a surface of the groove portion and a back surface of the mount portion are formed at the same height, and the heat receiving portion formed of a metal plate having higher thermal conductivity than the base plate is placed at the opening portion so that one surface of the heat receiving plate and a surface of the base plate on which the heat pipe is mounted form substantially the same plane.
 2. (canceled)
 3. The heat sink according to claim 1, wherein the heat receiving plate is fixed to the back surface of the mount portion.
 4. The heat sink according to claim 1, wherein the heat radiation fin has a plurality of fin plates equipped side by side, and the fin plates are arranged along an extension direction of the heat pipe.
 5. The heat sink according to claim 1, wherein the heat radiation fin has a plurality of reception grooves for receiving the heat pipe on a surface thereof which confronts the base plate, and a leg portion that comes into contact with the surface of the base plate is equipped between the reception grooves.
 6. The heat sink according to claim 3, wherein the heat radiation fin has a plurality of fin plates equipped side by side, and the fin plates are arranged along an extension direction of the heat pipe.
 7. The heat sink according to claim 3, wherein the heat radiation fin has a plurality of reception grooves for receiving the heat pipe on a surface thereof which confronts the base plate, and a leg portion that comes into contact with the surface of the base plate is equipped between the reception grooves.
 8. The heat sink according to claim 4, wherein the heat radiation fin has a plurality of reception grooves for receiving the heat pipe on a surface thereof which confronts the base plate, and a leg portion that comes into contact with the surface of the base plate is equipped between the reception grooves. 